Method of manufacturing a product dispensing system

ABSTRACT

In a method of manufacturing a dispensing system for dispensing a product from a canister, comprising a solid/gas arrangement in which the gas is adsorbed onto the solid under pressure and desorbed therefrom when the pressure is released and in which the solid comprises activated carbon and the gas comprises at least one of nitrogen, oxygen or mixtures thereof including air, carbon dioxide, nitrous oxide and argon, the canister having valve means to allow the gas adsorbed onto the carbon to be desorbed for generating a pressure in the canister and effect product dispense, the activated carbon is held from the time of its production up to its installation in the canister under a blanketing gas atmosphere which does not prevent the gas to be adsorbed from occupying the adsorption sites of the activated carbon in the canister.

This is a Divisional Application of U.S. patent Ser. No. 11/490,817filed Jul. 21, 2006 based on International patent ApplicationPCT/GB20051000145 filed Jan. 17, 2005 and claiming the priority of GBapplications 0401512.9, 0407991.9, 0419135.9, 0419137.9 and 0426490.9filed Jan. 23, 2004, Apr. 8, 2004 Aug. 27, 2004, Aug. 27, 2004 andrespectively, Dec. 2, 2024.

BACKGROUND OF THE INVENTION

The present invention relates to a method of manufacturing a system fordispensing substances from canisters and, more particularly, to such amethod employing a very simple but effective two phase solid/gasadsorption/desorption mode of operation.

A large number of products are on the general market packaged incanisters—some of which cause the product to be dispensed therefrom inthe form of small or atomized particles and are therefore commonlyreferred to as ‘aerosols’—which can be dispensed from the canister bymeans of a pressurized gas (or vapor) which is generated in situ in thecanister and acts as a dispensing or propellant gas. Such productsinclude ones for personal care including hair sprays, shaving creams,deodorants and the like and ones for household use including cleaningsubstances, room fragrances insect repellents and the like, and manymore.

In some cases, such products are admixed with the pressurized gas in thecanister and the operation of a (typically) push-down operating valvecauses both the product and the gas to be dispensed from the pack bymeans of the gas pressure via a ‘dip tube’ extending into the productand linked to a nozzle which is commonly associated with the releasevalve, all of which are commonly contained in a dispense assembly ordispense block.

In other cases, the product and pressurized gas are separated from eachother within the canister. Typically, some form of divider or membraneis present in the canister, for example, one in the form of a bagcontaining the product which is sealingly attached to the canisterinternal wail in the vicinity of the release valve; the gas is presentbetween the divider and the internal walls of the pack, i.e. surroundingthe bag and the gas pressure in turn exerts pressure on the product inthe bag.

Alternatively, the divider may be a piston which slides within thecanister with the product on one side and a gas on the other side andwhich acts to drive the product from the canister by the action of gaspressure.

Whichever type of pressure pack is adopted will depend on the nature ofthe product and the use to which it is to be put and on the nature andproperties of the propellant gas, in particular whether the propellantgas might react with the product or whether, for example, it might beflammable or odorize the product.

The use of chlorofluorocarbons (CFCs) previously became very popular aspropellant gases for such product dispense canisters in that they can bereadily condensed and vaporized in a reversible manner responsive to thesurrounding pressure. This was followed by the use of hydrofluorocarbons(HFCs) and also hydrochloroflurocarbons (HCFCs) which were regarded asbeing somewhat more environmentally friendly.

However, more recently, such propellant gases have in general beenphased out owing to their acknowledged environmentally harmfulproperties, in particular ozone depletion of the upper atmosphere.

Alternative propellant gases which have been commonly used are certainhydrocarbon gases including liquid petroleum gases (LPGs) such aspropane and butane. Such gases, however, are by their nature extremelyflammable, are environmentally harmful in some respects and in additioncan introduce an odour into the product being dispensed.

It is known that numerous attempts have been made to replace LPGpropellant gases with gases such as air, nitrogen, carbon dioxide andthe like. These attempts have largely been effected simply by utilizinga pressurized gas within the canister; in practice, the canister valveis depressed to propel the product from the canister in the generalmanner described above.

However such attempts have been largely unsuccessful due to the largepressure changes in the canister during use, commonly leading to reduceddispease characteristics at low pressures and a loss of pressure beforefull product dispense which results in a slow dispense of the lastproduct from the canister.

In addition, it is known that there has been considerable effort todevelop further alternative propellant systems for such productdispense. For example, there is disclosed in European Patent ApplicationNo, 385 773 the use of two-phase gas/solid or gas/liquid or three phasegas/liquid/solid propellant systems in which the solid is a polymerhaving molecular microvoids occupied by the gas or gas/liquid underpressure and the gas is released therefrom when the pressure of thesystem is reduced.

There is additionally disclosed in a further European Patent ApplicationNo. 502 678 the use of a three phase gas/liquid/solid propellant systemin which the solid is a material such as a foam or a fibrous mass havingopen voids occupied by the gas/liquid under pressure and the gas isreleased therefrom when the pressure of the system is reduced.

It is known that efforts to develop such prior systems were basedprimarily on the preferred embodiments described in these Europeanapplications, namely the use of a gas/liquid/solid system in whichcarbon dioxide as the gas was dissolved in acetone as the liquid whichitself occupied voids in a solid.

The use of acetone as the liquid in such a system would generally meanthat it was useful only in canisters employing a membrane, for example abag containing the product, in order to separate the propellant systemfrom the product to be dispensed. However, acetone is an aggressivechemical and it is also known that it was found that the use of acetonein such systems tended to cause problems associated with chemical attackof the membrane material and leakage of the acetone through and aroundthe membrane and resulting failure of the membrane.

A further prior attempt to produce a product dispense system utilizinggas pressure is disclosed in UK Patent Specification No. 1 542 322 inwhich a propellant gas, including propane/butane, certain CFCs andcarbon dioxide, is adsorbed onto a solid with the dispense gas pressurebeing produced in situ during use of the system by means of bringing thesolid into contact with a propellant displacing agent—preferablywater—in order to release the adsorbed gas. As such, the system as awhole is necessarily very complex due in particular to the need toemploy the propellant displacing agent during use and provide means tobring it into contact with the solid.

It is therefore the object of the present invention to provide animproved method of manufacturing an aerosol propellant system thatovercomes the problems associated with currently available systems.

SUMMARY OF THE INVENTION

In a method of manufacturing a dispensing system for dispensing aproduct from a canister, comprising a solid/gas arrangement in which thegas is adsorbed onto the solid under pressure and desorbed therefromwhen the pressure is released and in which the solid comprises activatedcarbon and the gas comprises at least one of nitrogen, oxygen ormixtures thereof including air, carbon dioxide, nitrous oxide and argon,the canister having valve means to allow the gas adsorbed onto thecarbon to be desorbed for generating a pressure in the canister andeffect product dispense, the activated carbon is held from the time ofits production up to its installation in the canister under a blanketinggas atmosphere which does not prevent the gas to be adsorbed fromoccupying the adsorption sites of the activated carbon in the canister.

The gas is preferably carbon dioxide in view of its generally superioradsorption characteristics in relation to activated carbon as anadsorbent.

The term ‘adsorbed gas’ used herein refers to the gas used in theinvention.

It has been surprisingly found that the method can provide the basis foran efficient, safe, reliable and reproducible system for productdispense.

It has been found in particular that the new method of manufacturing thedispense system can provide—by protecting the activated carbon employedalready before its installation in the canister, the amount of carbon,the initial pressure and therefore the amount of gas adsorbed on thecarbon—for a low pressure change during intermittent use between aninitial product dispense and full product dispense from a canister.

The pressure change afforded by the invention between a ‘full’ and‘empty’ canister is such that the canister in which it is positioned canmaintain an effective discharge of the product with an effective andacceptable controlled spray pattern in terms in particular of its beinguniform and/or homogeneous with a predetermined particle size anddistribution.

Systems of the invention have been shown to be particularly suited tothe dispensing of products from small, hand-held ‘aerosol’ canisters,for example ones having a 200 or 300 ml capacity. The term ‘aerosol’when used herein includes any hand-held dispensing devices for thedelivery of product whether or not the product is actually atomized orwhether or not it incurs any other form of product break-up.

In the implementation of the invention, and a first embodiment thereof,the dispensing system is preferably incorporated into a canister inwhich a product to be dispensed is held under gas pressure. In such anembodiment, carbon dioxide desorbed from the carbon adsorbentpressurizes the canister and maintains the pressure therein generallyand during actuation of the canister dispensing valve in particular.

Preferably, the product and the solid/gas arrangement are present inseparate compartments in the canister. This is primarily to keep theproduct and the solid apart from each other in order to hold the solidin a predetermined part of the canister and/or to ensure in particularthat the product, which may for example be in aqueous or other type ofsolution, does not contaminate the solid and, thereby detract from itsefficiency of adsorption.

In some instances, the compartments may be separated by means of awholly or substantially impermeable membrane. This membrane may take theform of a flexible bag which is sealingly attached either to theinterior wall of the canister or to the canister operating valve ordispense block and which in use holds the product to be dispensed. Thesolid/gas arrangement is generally positioned within the canisteroutside the bag such that pressure is exerted on the exterior of the bagwhen pressure therein is released on actuation of the valve and aproduct is dispensed via the valve through a nozzle. An elastic materialmay be employed to form the bag. Furthermore, the membrane, whether ofelastic or non-elastic material may be used and may be sealinglyattached to any relevant part of the canister interior.

The substantially impermeable membrane may alternatively take the formof a piston slidably mounted in the canister interior with the gas/solidarrangement on one side of the piston and the product to be dispensed onthe other side such that actuation of a dispense valve causes pressurefrom gas desorbed from the solid to move the piston and urge the productto be dispensed from the canister via the valve.

In other instances, the compartments may be separated by means of afixed partition. Such a fixed partition may usefully be positioned inany useful part of the canister and preferably include the base thereof,to form the solid/gas arrangement compartment therein. It can, forexample, be a concave-shaped disc in ‘flat’ canister base or one ofgreater concavity than the (usually) concave-shaped canister base (asviewed from the exterior of the canister). It may advantageously becrimped to the canister between the canister wall(s) and its base toform an annular compartment between the disc and the base.

The solid compartment may also be in the form of a container or ‘widget’that may be fixed to the canister (or part thereof) or allowed to befree within the canister interior.

In addition, the carbon container may be associated with the canisterdip tube, for example by being mounted around the dip tube for ease ofassembly of the canister generally and the positioning of the containertherein and, separately to allow for a ready filling of the containerwith adsorbed gas via the dip tube and via a one-way valve therebetween.

Generally, the product and the solid/gas arrangement of the dispensingsystem of the invention are present in individual compartments in thecanister, which are separated by a partition which may be fixed ordisplaceable. This keeps the product and the solid apart from each otherin order to hold the solid in a predetermined part of the canisterand/or to ensure in particular that the product, which may for examplebe in aqueous or other type of solution, does not contaminate the solidand thereby detract from its efficiency of adsorption.

With a fixed partition, for example the substantially rigid wall of thecarbon container, it is generally required that the gas from thesolid/gas compartment can flow into the product compartment, but notvice versa, and this can readily be effected by having a one-way valvein the partition.

Equally, there is a general need to provide means to allow theintroduction of carbon dioxide into the solid/gas compartment prior touse of and during use of the system; this can also be effected by aone-way valve to prevent back flow of the gas from the solid/gascompartment.

Each one-way valve should be designed such that it operates only under acertain applied pressure, for example a small fraction of 1 bar;otherwise the valve does not open.

With certain valve designs, it is possible for a single valve to operateseparately as a pressure sensitive valve in either direction dependingon the requirements of the system.

In such embodiments, the container for the carbon should have one-wayvalve means in order to allow the carbon dioxide to be desorbed from thesolid and pass into the product compartment when the pressure in thecanister falls, ie on operation of the canister dispensing valve, andthereby maintain canister pressures at predetermined levels for furtheruse of the aerosol.

In all cases, the one-way valve means may be made from any material andbe of any suitable form including ones incorporated integrally into thebody of the carbon container. One form which is particularly useful maycomprise an upstanding valve body terminating in a parallel, doubleplate arrangement—preferably formed integrally with the wall of aproduct bag or fixed partition—such that the plates act as a closedvalve in their usual position but which can move under their inherentresilience to an open position by virtue of gas pressure impingingthereon in a predetermined (single) direction, ie from the interior ofthe carbon container; such a valve is sometimes referred to as a‘sphincter’ valve.

The one-way valve advantageously is formed integrally with the partitionand is preferably made from a plastic material, for example PET orsilicone rubber.

With a displaceable partition, this will generally be impermeable to thegas and may take the form, for example, of a bag for holding the productor a piston slideable within the canister with the desorbed gas from thecarbon deforming the bag or moving the piston within the canister underthe increased gas pressure applied thereon during actuation of thedispensing valve.

In different embodiments of the invention, the dispensing system may beimplemented with a product not held before its dispense under gaspressure. In such embodiments, the desorbed gas is not used to effectproduct dispense until it is required in use. These embodiments may beput into effect by restraining the gas pressure in the solid/gascontainer and effecting its release therefrom via valve means only whenrequired during product dispense.

In these different embodiments of the invention, the desorbed gas may beused to effect product dispense by

i) causing the desorbed gas pressure to act directly on a product toeffect product dispense, for example by urging the product through a diptube inserted into the product in the canister, or

ii) causing the desorbed gas pressure to act indirectly on the productto effect product dispense, for example by its acting on a pistonslideably supported in a canister body or part thereof, or

iii) causing the desorbed gas to effect product dispense by fluiddynamic (fluidic) action through the formation of a vacuum into which aproduct is drawn, sucked or otherwise urged, for example by causingdesorbed gas to flow through a venturi in which the gas flow isincreased and the pressure is decreased in the ‘throat’ thereof, ie apartial vacuum is formed, and to which the product container can belinked to effect product dispense.

In these separate embodiments of the invention, it may beadvantageous—especially in regard to paragraphs i) and ii) above—toprovide valve means to release the pressure applied directly orindirectly to the product to effect its dispense when the canister isbeing used.

Use of the separate embodiments with an unpressurized canister isparticularly useful in the case of a product in which the propellant gascan dissolve.

In all embodiments, the carbon is advantageously held in a containerwhich is preferably proximate to the dispensing block, for example bybeing attached thereto or may be less firmly linked, for example via atube through which the carbon dioxide can be introduced into thecontainer.

In such preferred embodiments, the dispensing block itselfadvantageously incorporates a canister dispensing valve and passagewayslinking the interior of the canister with the exterior thereof via thevalve. As such, the dispensing block, together with the carboncontainer, can readily and effectively be sealingly inserted into anaperture in the canister during canister assembly.

In particular, the linkage of the container to the dispensing blockgenerally allows firstly for a ready operation of the pressure pack andsecondly allows for a simple mode of manufacture and assembly of theaerosol canister by allowing for the dispensing block—incorporating thecanister dispensing valve, necessary passageways linking the interior ofthe canister with the exterior thereof, and also the carbon containerlinked thereto—to be inserted into an aperture in the canister, ideallythe top of the canister, advantageously in a single assembly step.

The invention therefore allows canisters of standard designs to beemployed without modification to the body thereof in order to suitimplementation of the invention generally and to include canisters madeof either steel or aluminum or other material.

In preferred embodiments, the dispensing block and the carbon containerare advantageously joined, for example by being made as an integrallyformed unit, for example with the carbon container being situatedbeneath the dispensing block in a normal upright orientation of thecanister. It is also advantageous for a dip tube to depend from thedispensing block, preferably being positioned centrally (axially) in thecarbon container and, during use of the propellant system, extendinginto the body of the canister which includes the product to bedispensed.

The container for the carbon can be, for example, made of a flexibleplastic/polymer material in the form of a bag or alternatively becylindrical in shape and advantageously made from a more rigid material,again preferably from a plastic/polymer material. The container ispreferably cylindrical in shape.

In general, it is preferred for the carbon to be placed in the containerprior to the final assembly of the canister, i.e. prior to insertion ofthe dispensing block and into the product itself to which the containeris linked into the canister aperture as described above.

The product to be dispensed by the system of the invention is commonlyinserted into the canister via a dip tube depending from the dispensingblock and through which, during use of the aerosol, the product isdispensed via the dispensing valve in the reverse direction. Thesolid/gas container is advantageously linked to the dispensing block,for example by being positioned co-axially about the dip tube and assuch can be regarded as an integral part of the dispensing block. Insuch cases; the block as a whole can therefore readily be placed in acanister aperture simultaneously during assembly of the canister.

Means must also be provided for the introduction of the gas underpressure into the carbon container in order to cause it to be adsorbedonto the carbon and subsequently desorbed therefrom on operation of thedispensing valve. This can be effected, for example, by providing asuitable route via the dispensing block into the container interior andincluding (as described above) a one-way valve to prevent back flow ofthe gas.

Overall, therefore, and in all embodiments of the invention, the productdispensing system provides a simple and effective way of utilizing gasdesorbed from the adsorbent per se in order to provide a sufficient gasvolume to produce an initial gas pressure and thereafter to maintain gasvolumes, and necessary gas pressures, to enable a complete productdispense to be effected.

In all embodiments of the invention, a pressure regulator may be used toregulate the gas pressure released from the adsorbent of the dispensesystem of the invention to a predetermined pressure level or within apredetermined range of pressure. For example, a 10 bar(a) pressureprovided by desorbed gas may be regulated to produce propellant gas at 3bar(a).

With regard to the gas, it should be introduced into the dispensingsystem under pressure and which will be adsorbed onto the carbon suchthat its molecules are much more closely packed together than in theusual gaseous form at the same temperature and pressure.

This means that, when the gas is introduced under pressure into a gasspace” surrounding the carbon, considerably more gas will be adsorbedonto the carbon. Consequently, as the system is activated, typically byactuating the pressure release valve, there will in practice be only arelative and surprisingly small pressure reduction within the systemwhich, in use of the system, therefore allows for the effectivedispensing of all of the product.

In preferred embodiments utilizing carbon dioxide gas, it is injectedinitially under pressure in liquid form, for example down a dip tubedepending from or integrally formed with the valve block.

Adding the carbon dioxide in this way will generally produce a mixtureof carbon dioxide snow and cold carbon dioxide gas.

Using carbon dioxide in the form of a liquid or snow can in practice atleast partially thermally balance the heat of adsorption of the carbondioxide onto the carbon and maintain temperatures close to ambient.

A double valve arrangement may be employed for measuring exactquantities of liquid carbon dioxide present between two valvespositioned in a delivery tube of constant cross-section so as to definethe required volume of gas needed for each canister as they pass along aconveyor assembly line. This is preferably effected by closing theupstream valve once the required volume of carbon dioxide is presentbetween the valves and allowing the volume to vaporize, and to urge thestream of snow/gas into the canister.

The gas may also be charged into the container in the form of solidcarbon dioxide which is easy to handle and affords the benefitsdescribed above for liquid carbon dioxide.

In general, it is beneficial to charge the gas into the container bymeans other than a ‘bung hole’ in the base of the canister as thepresence of a bung hole may lead to gas leakage during storage/use ofthe canister.

Activated carbons are well known per se and have the advantage that theyare relatively inexpensive; they are non-polymeric substances. Ingeneral, activated carbons are manufactured from a variety ofcarbonaceous materials including (1) animal material (blood, flesh,bones, etc), (2) plant materials such as wood, coconut shell, corn cobs,kelp, coffee beans, rice hulls and the like and (3) peat, coal, tars,petroleum residues and carbon black.

Activation of the raw carbonaceous materials can be effected in avariety of known ways including calcining at high temperature (e.g. 500°C.-700° C.) in the absence of air/oxygen followed by activation withsteam, carbon dioxide, potassium chloride or flue gas at, say, 850° C.to 900° C., followed by cooling and packaging,

Selected activated carbons are suitable for use in the systems of theinvention, for example ones having a density of from 0.2 g/cm³ to 0.55g/cm³, preferably 0.35 g/cm³ to 0.55 g/cm³.

The quantity of carbon required in implementing the invention will varydepending on parameters including the gas employed, the initial andfinal pressures during the dispense of product, the nature of theproduct and its physical characteristics and the desired properties ofthe dispensed product. As such, the carbon may advantageously occupyfrom 5 to 95% of the canister interior volume.

In the case of a standard size (300 ml) canister, it is preferred formany product types to have a carbon content of from 5 to 30% of carbon(by volume) which generally equates, for selected carbons, to thepresence of 10 to 60 ml of carbon, more preferably 30 to 50 ml ofcarbon, for example 40 ml of carbon.

With other product types, especially those of relatively highconcentration of active ingredient(s), the carbon content may usefullybe from 30 to 95% preferably from 60 to 90%.

In the case of the higher concentration products in particular, but alsogenerally, the product dispensed from the nozzle of a canisterincorporating a system of the invention may advantageously be improvedby causing a separate bleed of gas to be directed into the dispensingvalve or block and therein to mix with the product being expelledtherefrom in order to effect a greater dispersion of the dispensedproduct.

Such improvements are especially useful with more concentrated and/ormore viscous products which might otherwise be difficult to disperseadequately for obtaining an effective spray pattern or whatever.

In preferred embodiments of the invention, the activated carbon ispresent in the form of one or more pellets or torroids, ie in a muchlarger size than the granules in which it is normally supplied, forexample of a size of at least 0.5 cm in length or greater. Such pelletsor torroids may be fabricated by sintering or other binding processesand preferably will allow for a much larger surface area for the carbondioxide and therefore a commensurately larger and more effective gasrelease on a reduced pressure.

The pellets or torroids can advantageously be manufactured as sticks ortubes and/or with surface ribs or grooves or with aperturestherethrough; all such forms can be capable of aidingadsorption/desorption of the gas.

In general, specific ways of treating and/or handling the carbon areimportant aspects of the invention and may be essential for theimplementation of dispensing systems of the invention.

In particular, it has been found that there may be a propensity for therequired properties of the carbon to degrade after the carbon activationprocess. Such degradation may include adsorption sites on the carbonbeing blocked by a gas or gases present in the atmosphere present aroundthe carbon and which cannot subsequently be displaced by the gas that isto be adsorbed as the working gas in the dispensing systems of theinvention. Although the blocking process may be reversible in certaincases, displacement by the preferred gas may not be effected completelyand therefore would detract from the subsequent adsorption of the gas.In some instances, desorption of the initially held gas may be aided byhigh temperature and/or vacuum.

In accordance with preferred aspects of the invention, therefore, theactivated carbon is held, advantageously from the time of itsproduction, under a blanketing atmosphere; this atmosphere may comprisethe adsorbed gas itself, or a gas or gases (including mixtures with theadsorbed gas) that do not prevent the adsorbed gas subsequentlyoccupying the carbon adsorption sites, in particular by virtue of beingheld at the adsorption sites on the carbon less strongly than theadsorbed gas.

Certain gases, including water vapor, are more strongly held at thecarbon adsorption sites than the adsorbed gas and carbon dioxide inparticular and therefore should be rigorously excluded from theatmosphere around the carbon; subsequent attempts to dislodge thestrongly held gases will not be successful.

Although some gases are less strongly held at the adsorption sites thancarbon dioxide and other adsorbed gases, they may still interfere withthe subsequent adsorption efficiency characteristics of the adsorbed gasand should be avoided as blanketing gases.

In the case of carbon, dioxide as the adsorbed gas, the blanketingatmosphere preferably includes or comprises carbon dioxide itself. Thiscan be especially advantageous in the implementation of the invention indispensing systems when the carbon dioxide is preferably adsorbed ontothe carbon at elevated temperatures. Other suitable gases include heliumand hydrogen which are generally capable of being displaced from theadsorption sites by carbon dioxide. The potential use of otherblanketing gases can be established by a skilled adsorption scientist ona theoretical or practical basis.

Adsorption is an exothermic process in which considerable amounts ofheat may be generated. The adoption of these preferred embodiments witha blanketing atmosphere that includes carbon dioxide itself isbeneficial in that it allows an initial level of adsorption of carbondioxide to occur—together with a dissipation of the generated heat—priorto the use of the carbon in dispensing systems of the invention. Thiscan lead to significant advantages from the resultant lower amounts ofheat generated when the remaining carbon dioxide is adsorbed underpressure in subsequent high speed production of canisters incorporatingthe dispensing systems of the invention.

With all adsorbed gases, the blanketing of the carbon is preferablyeffected from the time of cooling and is preferably maintainedcontinuously up to the time of (final) assembly of the canisters inwhich the dispensing systems are employed. To achieve this, the use ofcontainers for holding the blanketed carbon is required in order toisolate the carbon from undesirable gases.

In any event, the carbon granules or pellets or torroids mayadvantageously be pre-saturated with carbon dioxide (or other adsorbedgas) prior to use in order to improve the adsorption parameters. Thegranules/pellets/torroids may be advantageously cooled in suchpre-saturation processes by use of cooled carbon dioxide, for examplesolid carbon dioxide or snow being in contact with the granules orpellets.

In preferred embodiments and as stated above, the carbongranules/pellets/torroids are usefully kept in contact with a source ofcarbon dioxide or other adsorbed gas, especially cold gas, liquid orsnow, prior to placement in a canister and this may provide sufficientadsorbed gas for use in the system without the need to add furtheramounts of gas.

In the case of certain products, it has been found that it may be usefulfor optimum dispense characteristics to pre-treat the product withadsorbed gas prior to, or during, its introduction into the canister.This can be especially useful in the case of highly soluble gases suchas carbon dioxide, ie ‘pre-carbonation’. Such a process is more usefulin the case of product to be admixed with the adsorbed gas in thecanister; it may, however, also apply to product present in the canisterseparated from the adsorbed gas by a moveable partition including a bagwhether or not the partition allows for a certain leakage of gastherethrough.

Working canisters incorporating the product dispense systems of theinvention have been made to good effect in terms in particular ofinitial and final gas pressures during full product dispense asexemplified below with carbon dioxide adsorbed as in particular:

Canister volume 300 ml Carbon volume  50 ml ‘Free’ canister volume 250ml Liquid product volume 225 ml Initial gas pressure  6 bara Final gaspressure  4 bara (following full product dispense)

Tests on a canister containing a larger carbon to product volume ratioresulted in a proportionately lower change between initial and finalpressures.

All tests were conducted using activated carbon samples treated andhandled with a carbon dioxide blanketing atmosphere from the time ofcooling during production of the carbon.

Tests with other adsorbed gases produced similar results depending onthe adsorption characteristics of the individual gases.

The invention will be described below in greater detail with reference,by way of example only, to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic vertical section through a canisterincorporating a dispensing system of the invention;

FIG. 2 shows a sectional view through the canister of FIG. 1 along theline II-II; and

FIG. 3 shows a schematic vertical section through a canister ofdifferent design to that of FIG. 1 incorporating a dispensing system ofthe invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the drawings and to FIG. 1 in particular, there isshown a canister 1 incorporating a pressure pack dispensing system ofthe invention. The canister 1 comprises a cylindrical main body portion2, a circular base portion 3 of concave shape (external view) and acircular top portion 4 of convex shape (external view), all made ofaluminum alloy material.

The base portion 3 is sealingly crimped around its periphery to thelower edge of the main body portion 2 in a manner known per se foraerosol canister in particular.

Sandwiched and sealingly held within the crimped structure between themain body portion 2 and the base portion 3 is a circular partition 5made of plastic and having a greater concavity shape than the baseportion 3.

The base portion 3 has a small circular “bung” 6 at its centre made ofrubber (or other elastomer) and the partition 5 has an upstandingone-way valve 7 allowing for the flow of fluid from a compartment 8formed between the base portion 3 and the partition 5 and into the uppercompartment containing the substance to be dispensed but not vice-versa.

The one-way valve 7 comprise two upstanding plates 9, 10 (see FIG. 2)which are formed integrally with the partition 5 and which, by virtue ofthe relative positioning of the plates 9, 10 and the nature of theplastic material from which they are made, are biased to lie adjacenteach other in the vicinity of their ends furthest from the partition 5.

As such, the one-way valve 7 will open by parting the plates 9, 10 whenthere is, in use, an excess pressure in the compartment 8 over that inthe interior of the remainder of the canister 1.

The plates 9, 10 will not part and the valve 7 will therefore notoperate in the opposite direction as any excess pressure in the canister1 will not cause such parting by virtue of the shape of the adjacentends of the plates.

The top portion 4 is sealingly crimped around its periphery to the upperedge of the main body portion 2 again in a manner known per se foraerosol canisters in particular.

Positioned centrally of the top portion 4 in an aperture thereof is anoperating valve system 11 comprising a valve seat 12 against which aball valve member 13 is in its “closed” position held but which can beunseated in its “open ” position by depression of an operating button 14against the action of a spring 15. Release of the button 14 causesre-seating of the valve member 13 by means of the spring 15.

A tube 16 depends downwardly from the valve system 11 and a dischargeline for the substance to be dispensed is formed from the lower end ofthe tube 16, through the tube 16 itself and via the valve mechanism to adischarge port 17 in the operating button 14.

In the manufacture of the canister 1, activated carbon 18 is included inthe compartment 8 between the base portion 3 and the partition 5 and thesubstance to be dispensed is charged into the canister 1 above thepartition 5 via the aperture in the top portion prior to installation ofthe valve system 11.

With the valve system 11 in place, carbon dioxide gas or liquid isloaded into the compartment 8 by means of a needle injection through therubber bung 6, causing its adsorption into the activated carbon 18 inthe compartment 8.

The carbon dioxide gas pressure in the compartment 8 equalizes thepressure in the canister 1 surrounding the substance to be dispensed viathe one-way valve 7.

In use of the canister 1, the carbon dioxide pressure generated by thepressure pack system of the invention will, when the operating button 14is depressed, urge the substance being dispensed from the canister 1 viathe tube 16 and the valve system 11 and the discharge port 17.

With reference to FIG. 3, there is shown a canister 31 incorporating apressure pack dispensing system of the invention. The canister 31comprises a cylindrical main body portion 32, an integrally formedcircular base portion 33 of concave shape (external view) and a circulartop portion 34 of convex shape (external view), all made of an aluminumalloy material.

Positioned centrally of the top portion 34 is an aperture 35 andsealingly held therein is a dispensing block 36 having a main passageway37 therethrough and an associated valve 38 for allowing, in use, productto be dispensed from the interior of the canister. Biasing means, forexample a spring (not shown), urges the valve towards a closed position.

The passageway 37 is linked at one end to a reciprocatable valveactuating hollow tube 39 and at the other end to a ‘dip’ tube 40extending into the main body portion 32.

An operating cap 41 is positioned over the dispensing block 36 andmovement (depression) thereof towards the body portion 32 actuates thehollow tube 39 and causes opening of the valve 38.

A further passageway 42 in the dispensing block 36 has an openingadjacent the operating cap 41 and extends into the interior of acanister 44 attached to the dispensing block 36 and forming an integralunit therewith.

A one-way valve 45 is present in the passageway 42 to allow flow offluid into the container 44 but not vice versa. A further one-way valve46 is present in the base of the container 44 to allow flow of carbondioxide from the container 44 and into the canister 31 when the pressurein the canister falls below that of the container 44.

In assembling the canister including the pressure pack of the invention,the dispensing block 36 (to include the dip tube 40 and the linkedcontainer 44) is sealingly inserted into the aperture 35 in the canistertop portion in a single assembly step.

The canister is filled with liquid product to be dispensed via a needleinserted into the hollow tube 39 and operates to open the valve 38against the action of the biasing means in order to allow the liquid toflow through the passageway 37 and dip tube 40 and fill the canister upto the product level 47.

The container 44 is pre-packed with activated carbon held under anatmosphere of carbon dioxide since its production and additionallypre-flushed with carbon dioxide. After insertion of the dispensingblock, etc into the aperture 35 and product into the canister interior,a source of carbon dioxide gas under pressure is attached to thepassageway 42 for pressurization of the container 44 via the one-wayvalve 46 and to cause the adsorption of the carbon dioxide onto theactivated carbon in the container. The presence of the further one-wayvalve 46 allows the carbon dioxide to pressurize the head space abovethe product in the canister 31 until the respective pressures aresubstantially equalized.

The operating cap 41 is then fitted over the dispensing block and theaerosol canister is ready for use. Depression of the operating cap 41moves the tube 39 and actuates the valve 38 to allow product to pass upthe dip tube 40 and be dispensed from the canister via the passageway37, the tube 39 and a passageway (not shown in the operating cap 41 to anozzle 48 in the cap 41, all under the carbon dioxide gas pressurepresent in the head space.

Resulting loss of carbon dioxide pressure in the head space isreplenished by an automatic flow of gas from the container 44 via theone-way valve 46. Pressure in the container 44 itself is maintained bydesorption of further gas from the activated carbon.

What s claimed is:
 1. A method of manufacturing a dispensing system fordispensing a product from a canister, comprising a solid/gas arrangementin which the gas is adsorbed onto the solid under pressure and desorbedtherefrom when the pressure is released and in which the solid comprisesactivated carbon and the gas comprises at least one of nitrogen, oxygenor mixtures thereof including air, carbon dioxide, nitrous oxide andargon, the canister having valve means to allow the gas adsorbed ontothe carbon to be desorbed for generating a pressure in the canister andeffect product dispense, said method comprising the step of holding theactivated carbon from the time of its production up to its installationin the canister under a blanketing gas atmosphere which does not preventthe gas to be adsorbed from occupying the adsorption sites of theactivated carbon in the canister.
 2. The method according to claim 1,wherein the blanketing gas comprises one of carbon dioxide, helium andhydrogen.
 3. The method according to claim 1, wherein the adsorbent gascomprises carbon dioxide and the blanketing gas comprises also carbondioxide held under gas pressure.
 4. The method according to claim 1,wherein the product is pre-treated with adsorbed gas prior to, orduring, its introduction into the canister
 5. A dispensing system forthe method as defied in claim 1, including a canister with individualsolid/gas compartments wherein the product and the solid/gas arrangementof the dispensing system are present in the canister in different solid/as compartments.
 6. The dispensing system according to claim 5, whereinthe different compartments are separated by a fixed partition.
 7. Thedispensing system according to claim 6, wherein the differentcompartments are solid/gas and product compartments divided by apartition and a one-way valve is disposed in the partition forcontrolling the flow of gas from the solid/gas compartment into theproduct compartment.
 8. The dispensing system according to claim 5,wherein a one-way valve is arranged in the carbon container to preventback flow of the gas from the solid/gas compartment in order to allowthe introduction of carbon dioxide into the solid/gas compartment andretain it therein prior to, and during, use of the system.
 9. Thedispensing system according to claim 5, wherein the product of and thesolid/gas arrangement of the dispensing system are present in thecanister in individual compartments, which are separated by adisplaceable partition impermeable to the gas.
 10. The dispensing systemaccording to claim 5, wherein the canister includes a dispensing blockand the carbon canister and the dispensing block are an integrallyformed unit.